Screw-on electrical connector

ABSTRACT

A screw-on type wire connector includes a housing tubular shell member closed at its distal end and formed of a deformable insulating plastic material and has an axial bore including a proximal inwardly tapered throat section joining an inwardly tapered intermediate section provided with longitudinally extending raised flats arranged in quadrature and joining by a tapered shoulder, a slightly tapered distal bore of reduced cross section. A tapered elongated helical wire coil nests in the housing bore with its narrow inner end force fitted in the distal bore and extending short of the closed end and the wide end of the coil engaging and distorting the flats in the intermediate bore section. Upon application to a pair of wires, the coil selfthreads into the flat faces and distal bore face.

United States Patent [191 Norden [451 Aug. 26, 1975 1 SCREW-ON ELECTRICAL CONNECTOR [75] Inventor: Alexander R. Norden, New York,

[73] Assignee: l-T-E Imperial Corporation, East Farmingdale, NY.

[22] Filed: Mar. 4, 1974 [21] Appl. No.: 447,803

Primary E.\'anziner-Darrell L. Clay Attorney, Agent or FirmHoward C. Miskin [57 ABSTRACT A screw-on type wire connector includes a housing tubular shell member closed at its distal end and formed of a deformable insulating plastic material and has an axial bore including a proximal inwardly tapered throat section joining an inwardly tapered intermediate section provided with longitudinally extending raised flats arranged in quadrature and joining by a tapered shoulder, a slightly tapered distal bore of reduced cross section. A tapered elongated helical wire coil nests in the housing bore with its narrow inner end force fitted in the distal bore and extending short of the closed end and the wide end of the coil engaging and distorting the flats in the intermediate bore section. Upon application to a pair of wires, the coil self-threads into the flat faces and distal bore face.

10 Claims, 4 Drawing Figures 1 SCREW-ON ELECTRICAL CONNECTOR BACKGROUND OF THE INVENTION The present invention relates generally to improvements in electrical connectors and it relates more particularly to an improved screw type electrical connector for providing a secure coupling between the free ends of electrical wires without the need for soldering or special tools.

The conventional screw type electrical connector of the subject nature generally includes a tubular shell closed at one end and formed of an insulating plastic material and a tapered helically wound resilient wire coil nested and anchored in the shell. While this type of electrical connector has many desirable features, those heretofore available and proposed possess numerous drawbacks and disadvantages. They are often unreliable and are frequently difficult to assemble and employ and are of limited application. Moreover, their manufacture present many problems and thus increase their cost and limit the materials from which they may be constructed and they have little versatility and adaptability and otherwise leave much to be desired.

SUMMARY OF THE INVENTION It is a principal object of the present invention to provide an improved electrical connector.

Another object of the present invention is to provide an improved easy to assemble electrical connector for joining the ends of a wide variety of sizes of conductor wires without the use of soldering or tools.

Still another object of the present invention is to provide an improved two-piece screw type electrical connector which is easy to use and provided with an outer shell which houses a helical wound tapered wire coil.

A further object of the present invention is to provide an electrical connector of the above nature characterized by its reliability, ruggedness, low cost, ease and convenience of assembly and application and great versatility and adaptability.

The above and other objects of the present invention will become apparent from a reading of the following description taken in conjunction with the accompanying drawing which illustrates a preferred embodiment thereof.

In a sense the present invention contemplates the provision of an improved screw type electrical connector which comprises a tubular outer shell formed of a deformable insulating material and being closed at its distal end and open at its proximal end and being provided with an axial bore including a distal section of reduced widthand a proximal section of increased width and of noncircular transverse cross section and whose minimum width is greater than the maximum width of the distal bore section and an elongated helical wire coil housed in the bore sections and tapering forwardly inwardly from its proximal toward its distal end, the proximal portion of the coil having a diameter between the maximum diameter and distance between the flat faces of the proximal bore section and opposite faces of the proximal bore section being distorted by the coil proximal section.

In the preferred form of the improved connector the proximal end of the outer tubular shell has a wide forwardly inwardly tapered throat which joins the proximal bore section whose outer inside face is forwardly inwardly tapered. Four inwardly raised longitudinally extending projections are arranged in quadrature along the face of the proximal bore and are provided with flat faces which lie in approximately mutually perpendicular planes and have peripherally spaced side edges and are gently forwardly inwardly tapered and join the face of the proximal bore near its distal end. A sharply tapered shoulder joins the distal edge of the proximal bore section to the proximal edge of the distal bore section, the latter having a gentle taper. The helical wire coil includes a tapered proximal section which distorts and is in an interference fit with the proximal bore flat faces and the distal portion of the wire coil is cylindrical and in interference fit with the distal bore section and before application extends to a point short of the end of the distal bore section.

The improved connector is simple, inexpensive, rugged and reliable. It is easy to manufacture and assemble, the wire coil being merely inserted and pressed into the shell bore and not requiring any turning. The coil can receive and grip a wide variety of sizes of eonduc tors. Moreover, the shell may be easily injection molded with simple molds and from a wide variety of plastic materials.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view, partially fragmented, of the housing shell of a preferred embodiment of the present invention;

FIG. 2 is an end view thereof taken along line 22 in FIG. 1;

FIG. 3 is a sectional view taken along line 33 in FIG. 2; and

FIG. 4 is a sectional view taken along line 44 in FIG. 2 illustrating the wire coil in assembled condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing which illustrates a preferred embodiment of the present invention, the reference numeral 10 generally designates the improved connector which includes an outer housing shell 11 and a helical wire coil 12 housed in the shell 11. The shell 11 is formed by conventional injection molding of any suitable deformable, thermoplastic synthetic organic polymeric resin such as a polyolefin, for example, polypropylene, polyvinyl chloride or the like, and the insert coil 12 is formed of a resilient metal wire, advantageously of square transverse cross section.

The shell 11 is of approximately hollow elongated conical shape being closed at its distal or front apex end 13, which has a rounded face and being open at its opposite rear proximal end which is somewhat flared. A pair of diametrically opposite outwardly directed longitudinal extending fins 14 are formed on the outer face of the shell 11 to facilitate the manipulation and application of the connector 10.

Formed in the front section of shell 11 is a short distal axial bore section 16 which is of circular transverse cross section and has a gentle inward forward taper. The front end of bore section 16 is closed and the front end face 17 thereof is conically shaped with a rearwardly directed axial apex. A sharply outwardly rearwardly tapered peripheral connecting shoulder 18 extends from the proximal edge of distal bore section 16 to the circular distal edge of an enlarged proximal coaxial bore section 19. The proximal bore section 19 includes a forwardly inwardly tapering inside bore face of somewhat greater taper and of greater length than distal bore section 16 and extends from the rear edge of shoulder 18 to a point short of the rear end of the shell 11.

A plurality of peripherally spaced longitudinally extending inwardly directed formations 21 are provided on the bore inside face 20 and although four formations 21 are illustrated arranged in quadrature about the axis of shell 11 more or less of such formations 21 may be providedv Each formation 21 extends from the rear to the front edge of bore face 20 and includes a flat inside face 22 slightly inwardly inclined to the shell longitudinal axis so as to converge with bore face 20 at its front edge and to extend inwardly from rear portion of bore face 20. The face 22 is of generally rounded triangular shape and includes a rear edge 23 disposed forwardly and inwardly of the rear edge of bore face 20 and is joined to bore face 20 by a rearwardly directed end face 24 which is forwardly inwardly inclined and joins the bore face 20 along a curved outer edge 26 whose medial portion joins the rear peripheral edge of bore face 20.

Extending coaxially rearwardly from the rear edge of proximal bore section 19 and delineated therefrom by a rearwardly facing peripheral shoulder 27 is a coaxial rearwardly outwardly flared throat bore section or skirt 28 which reaches the rear end of shell 11.

The helically wound wire insert coil 12 includes a forwardly inwardly tapered rear section 32 which occupies a major portion of the coil 12 and a substantially cylindrical front portion 33. The maximum diameter of the coil rear portion 32 at the open end thereof is of a .value between the diameter of bore face 20 at its rear border and the distance between diametrically opposed flat faces 22 at their rear borders. The wire 34 forming the coil 12 is of square transverse cross section with the opposing longitudinal corners of the wire 34 at successive convolutions being in contact to provide sharp outwardly and inwardly directed helical edges defined by the outer corners of the wire 34. The enlarged opening of coil 12 is slightly outwardly sprung to provide a tangentially projecting short leg 36.

In assembling the shell 11 and coil 12, the coil 12 is merely axially inserted and pressed into the bore of the shell 11 so that the coil rear portion 32 registers with proximal bore section 19, the rearmost section of coil rear portion 32 deforming the rear portions of flat faces 22 so as to be firmly engaged thereby and the coil front portion 33 projecting into and tightly engaging the face of distal bore section 16 but not extending to the base thereof.

In employing the connector 11, a pair of side by side wire conductors free of insulation at their end portions are inserted into the coil 12 as far as they will go and the connector 10 is turned clockwise relative to the wire conductor so that the coil 12 bites into and tightly compresses the wire conductors into a tight, firm interengagement in good electrical contact and with a se cure mechanical connection. With the turning of the connector 10, the shell 11 turns relative to the coil 12 so that the coil 12 rolls a mating thread in the faces 22 as well as in the face of distal bore section 16 and axially advances by turning in the self formed thread until the coil front portion 33 reaches the base 17 of bore distal section 16. Axial retraction of the coil 12 from the shell 1 l is prevented by the interference fit between the opposite ends of the coil and the correspondingly engaged faces of the shell bore and extraction rotation of the coil 12 is prevented by the end of tangential wire leg 36 biting into a bore face 22 upon counterclockwise rotation of shell 11 relative to coil 12 thereby preventing such rotation.

While there has been described and illustrated a preferred embodiment of the present invention, it is apparent that numerous alterations, omissions and additions may be made without departing from the spirit thereof.

What is claimed is: v

l. A screw type wire connector comprising a tubular shell formed of a deformable insulating material and being closed at its distal end and provided with an enlarged opening at its proximal end and having an axial bore including a distal section of reduced width and a proximal section of increased width and of non-circular transverse cross section and whose minimum width is greater than the width of said distal section, said proximal bore section having at least three longitudinally extending substantial flattened surfaces, said flattened surfaces facing said bore and substantially defining the periphery of a transverse cross section of said proximal bore section, and an elongated helical wire coil housed in said bore and having a distal end and a proximal end, said coil tapering inwardly from its proximal end toward its distal end, the proximal end of said coil having a diameter between the maximum and minimum widths of said proximal bore section and faces of said proximal bore section being distorted by said coil proximal portion.

2. The wire connector of claim 1 wherein said flattened faces lie approximately in the planes of the faces of a polygonal prism coaxial with said bore.

3. The wire connector of claim 2 wherein said proxi mal bore section has a tapered outer face rearwardly directed and radially inwardly projecting raised portions having inner surfaces defining said flattened faces.

4. The wire connector of claim 3 wherein said flattened faces are slightly forwardly tapered and joins said proximate bore tapered outer face proximate its distal end, said proximate and distal bore sections being joined by an inwardly forwardly tapered shoulder.

5. The wire connector of claim 3 including a rearwardly outwardly flared throat at said bore proximal end adjacent the proximal end of said proximal bore section.

6. The wire connector of claim 5 including a rearwardly facing peripheral shoulder joining said throat and said proximal bore section.

7. The wire connector of claim 1 wherein the distal end portion of said coil extends into said distal bore section to a point short of the closed end thereof.

8. The wire connector of claim 7 wherein said distal bore section is slightly forwardly inwardly tapered.

9. The wire connector of claim 7 wherein the distal end of said coil has an interference fit with the distal bore section.

10. The wire connector of claim 1 wherein the proximal end of the wire forming said coil projects tangentially outwardly. 

1. A screw type wire connector comprising a tubular shell formed of a deformable insulating material and being closed at its distal end and provided with an enlarged opening at its proximal end and having an axial bore including a distal section of reduced width and a proximal sEction of increased width and of non-circular transverse cross section and whose minimum width is greater than the width of said distal section, said proximal bore section having at least three longitudinally extending substantial flattened surfaces, said flattened surfaces facing said bore and substantially defining the periphery of a transverse cross section of said proximal bore section, and an elongated helical wire coil housed in said bore and having a distal end and a proximal end, said coil tapering inwardly from its proximal end toward its distal end, the proximal end of said coil having a diameter between the maximum and minimum widths of said proximal bore section and faces of said proximal bore section being distorted by said coil proximal portion.
 2. The wire connector of claim 1 wherein said flattened faces lie approximately in the planes of the faces of a polygonal prism coaxial with said bore.
 3. The wire connector of claim 2 wherein said proximal bore section has a tapered outer face rearwardly directed and radially inwardly projecting raised portions having inner surfaces defining said flattened faces.
 4. The wire connector of claim 3 wherein said flattened faces are slightly forwardly tapered and joins said proximate bore tapered outer face proximate its distal end, said proximate and distal bore sections being joined by an inwardly forwardly tapered shoulder.
 5. The wire connector of claim 3 including a rearwardly outwardly flared throat at said bore proximal end adjacent the proximal end of said proximal bore section.
 6. The wire connector of claim 5 including a rearwardly facing peripheral shoulder joining said throat and said proximal bore section.
 7. The wire connector of claim 1 wherein the distal end portion of said coil extends into said distal bore section to a point short of the closed end thereof.
 8. The wire connector of claim 7 wherein said distal bore section is slightly forwardly inwardly tapered.
 9. The wire connector of claim 7 wherein the distal end of said coil has an interference fit with the distal bore section.
 10. The wire connector of claim 1 wherein the proximal end of the wire forming said coil projects tangentially outwardly. 